System and method to cause an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles

ABSTRACT

A system and method to cause an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles are disclosed. A particular embodiment includes: an electronic system comprising: a protected electronic device; and an embedded obfuscation unit coupled with the protected electronic device, the embedded obfuscation unit including an obfuscation state machine, the embedded obfuscation unit further including control logic to: obtain a randomized seed value; extract a first number of bits from the randomized seed value, the first number of bits representing an initial obfuscation state; extract a second number of bits from the randomized seed value, the second number of bits representing a starting functional reset state; determine a number of traversal cycles needed to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state; and initiate a state traversal operation to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state in the determined number of traversal cycles.

PRIORITY PATENT APPLICATION

This is a continuation-in-part patent application claiming priority to U.S. non-provisional patent application Ser. No. 14/716,861, filed on May 19, 2015; and Ser. No. 14/804,284, filed on Jul. 20, 2015. This present continuation-in-part patent application draws priority from the referenced patent applications. The entire disclosure of the referenced patent applications is considered part of the disclosure of the present application and is hereby incorporated by reference herein in its entirety.

COPYRIGHT

A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to the hardware designs, software, and data as described below and in the drawings that form a part of this document: Copyright 2014-2016 Anvaya Solutions, Inc., All Rights Reserved.

TECHNICAL FIELD

This patent application relates to electronic systems, integrated circuit systems, static electronic devices, mobile electronic devices, electronic hardware and device design, electronic device fabrication, and computer-implemented software, according to various example embodiments, and more specifically to a system and method to cause an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles.

BACKGROUND

Advances in semiconductor processing and logic design have permitted an increase in the amount of logic that may be present on integrated circuit devices. As a result, computer system configurations have evolved from a single or multiple integrated circuits in a system to multiple hardware threads, multiple cores, multiple devices, and/or complete systems on individual integrated circuits. Additionally, as the density and complexity of integrated circuits has grown, the threat of unauthorized embedded hardware or software components has also escalated.

With the Time to Market (TTM) expectancy shortening in recent years, much of the microelectronics supply chain continues to be outsourced. Trust in the supply chain has been greatly eroded due to many different acts of piracy. This has raised significant questions about the integrity and authenticity of original Intellectual Property (IP) designs embedded inside an Integrated Circuit (IC) or other electronic device.

The following acts of IP piracy have significantly contributed to the erosion of trust in the IC device supply chain: 1) Counterfeiting where a substandard part, rejected part, or a cannibalized part from a previously used and discarded board is remarked as new and re-introduced into the supply chain; and 2) Overbuilding, where the silicon fab houses overproduce blind copies of the ICs in excess of authorization for their own spurious sale. Conventional technologies have been unable to effectively and efficiently provide defenses against these threats.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which:

FIG. 1 illustrates a system level operational processing flow of an example embodiment;

FIG. 2 is an architectural diagram illustrating the functional components provided in the example embodiment;

FIG. 3 is a high level block diagram illustrating the functional components and processes provided in the example embodiment;

FIG. 4 illustrates the authentication subsystem and authentication environment of an example embodiment;

FIGS. 5 through 8 are flowcharts illustrating an example embodiment of the processing operations performed as part of the authentication protocol by the authentication subsystem;

FIG. 9 illustrates an example embodiment of the data structures representing the exchanged device specific authentication information;

FIG. 10 is a processing flow chart illustrating an alternative embodiment of a method as described herein;

FIGS. 11 through 14 are flowcharts illustrating an example embodiment of the processing operations performed for causing an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles; and

FIG. 15 shows a diagrammatic representation of a machine in the example form of a computing and/or communication system within which a set of instructions when executed and/or processing logic when activated may cause the machine to perform any one or more of the methodologies described and/or claimed herein.

DETAILED DESCRIPTION

In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which are shown, by way of illustration, specific embodiments in which the disclosed subject matter can be practiced. It is understood that other embodiments may be utilized and structural or process changes may be made without departing from the scope of the disclosed subject matter.

According to various example embodiments of the disclosed subject matter as described herein, there is provided a system and method to cause an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles. The various embodiments described herein provide an embedded and active obfuscation system, which requires authentication of a protected electronic device after manufacturing and prior to any deployment. Once authentication of the protected electronic device is confirmed, the various embodiments described herein can activate the protected electronic device by causing the obfuscated non-functional protected electronic device to transition to a functional state using a specified number of cycles. This inventive system defeats the incorporation of a counterfeit device or an unauthorized overbuilt part into the supply chain. As described herein, the term “device” or “protected electronic device” can refer to a microelectronic integrated circuit device being protected by the systems and methods of the various embodiments described herein. In various embodiments, the protected electronic device can be an integrated circuit (IC), an electronic system or circuit board, and/or any other type of electronic device or system.

In a particular described embodiment, every protected electronic device performs a one-time authorization and authentication by the Intellectual Property (IP) owner (or other authorized representative) to function correctly on a new board or other electronic system into which the protected electronic device is embedded. Prior to authorization and authentication, the device can be initially activated (e.g., wake-up) in a unique-per-device obfuscated, non-functional mode on power-on. The device user can then connect with a protected system of the device IP Owner and request the execution of an authentication procedure to confirm the credentials of the device and the device user. A successful authentication will enable the IP Owner to issue an authentication key to the device user, which enables a transition of the operational mode of the device from the initial obfuscated, non-functional mode to a functional mode. The various embodiments described herein provide an embedded hardware method integrated in a per-device unique fashion, for transitioning the device from the non-functional obfuscated mode to the fully functional device mode.

Based on the inventive approach offered by the various embodiments described herein, the following advantages can be realized:

-   -   Any electronic device protected by the obfuscation technology         disclosed herein will be rendered non-functional after         manufacturing and prior to authentication. The protected         electronic device will require a one-time per board/system         authentication by the IP owner (or other authorized         representative) for the device to be operationally functional.     -   Such an authentication cannot be transferred to a different         board/system, which therefore prevents unauthorized reuse of the         protected device.     -   Similarly, a counterfeit part deployed for unauthorized reuse         remains functionally dead, as it will not be authenticated by         the IP owner (or other authorized representative) for such         unauthorized reuse.

The electronic device authentication and enablement system and method described herein eliminates the cumbersome burden of first detecting and then proving a spurious device in play in the supply chain. By use of the obfuscation technology disclosed herein, the producer, fabricator, or the end user of such a spurious device must first contact the IP owner to enable the device to function. By requiring this device authentication prior to use, the possessor of the spurious device is likely to be caught and most likely such an overbuilt/counterfeit device will remain inactive and prevent any damage to the supply chain. The deployment of an overbuilt or counterfeit part into the supply chain itself is thwarted, as such a part is rendered useless until authenticated. The systems and methods of the various embodiments described herein enhance the trustworthiness of the device in play in the supply chain, even as many of the elements in the supply chain remain untrustworthy. This should be compared against the current passive methods where there are no countermeasures to prevent the release of the spurious parts into the supply chain or, their eventual use in an end product (because they slipped through and never got detected). The conventional methods of post-deployment passive detection can therefore result in serious damage, possibly catastrophic damage, once the spurious part is fielded for use.

A fundamental goal of the various embodiments described herein is to have the protected electronic device converge from its native wakeup obfuscated mode to the starting functional reset mode in the specified number of clock cycles. The transition to a functional mode should not take more than the pre-determined number of cycles; because, an excessive number of cycles may violate the performance metric of the device. The transition to a functional mode should not take less than the pre-determined number of cycles; because, an insufficient number of cycles may dilute the obfuscation strength and thus the integrity of the device. A goal of the various embodiments described herein is to embed real confusion and deception into the operation of the device and thereby obfuscate the nefarious understanding or prediction of how the device transitions into the functional mode.

It is quite easy to design a device that can reach an initial functioning state from any obfuscated state in a very quick and definitively-timed manner. However, any observation of such a quick, predictable convergence to the functional start state will make it easy for a hacker to tamper or reverse-engineer the device to completely bypass the obfuscation logic and thus defeat the authentication process. The meandering traversal each device uniquely attempts through different state transition paths to finally reach its first functioning state facilitates confusion in understanding the device behavior. This confusion in understanding enhances the protection of the device IP. To bind the traversal path time for a particular device, the authentication key (from the IP Owner) sets a parameter to specify the time to be actually taken to perform the traversal from an obfuscated, non-functional state to the initial functional state.

Several important elements of an example embodiment of the method, which reinforces the layer of obfuscation while moving the device to a functional mode, include the following:

-   -   Every microelectronic device has a sea-of-states (e.g., a large         plurality of states) defining a master control state machine         (and also other lower state machines if desired). The bulk of         the states in the large plurality of states constitutes the         obfuscated logic, which renders the device non-functional. The         small remainder of the states in the large plurality of states         constitutes the functional logic, which renders the device         functional and allows for normal device behavior. Typically for         effective obfuscation, the ratio of the obfuscated-states count         to functional-states count should be a million-to-one or more.         This can be implemented with very little design overhead by         increasing the width of total state machine state bits (e.g.,         flops). For example, a state machine with a million states can         be easily realized using 20 flops to define the 2²⁰ or million         states. In practice, the width of the state machine state bits         should be even larger and in the range of 22 to 32 bits to         provide a total state machine state count between 4 million to 4         billion states. The number of functional states on the other         hand is typically only between 4 to 16 states. Thus, the desired         large ratio of obfuscation states to functional states can be         easily realized using the techniques disclosed herein.     -   The initial traversal through the large number of obfuscation         states to reach the starting functional state happens during a         mode denoted as the, “Convergence Window” time. During this         traversal, it is possible to hit some of the very few functional         states; however, encountering a functional state during the         traversal while in an active “Convergence Window” configured         mode, will have no impact on the traversal, which will continue         to proceed. This “Convergence Window” mode configures all         functional states to be dormant during this initial traversal.         Once the convergence to the first starting functional state is         accomplished, the “Convergence Window” mode closes and all         functional states will start exhibiting normal functional         behavior.     -   Every device wakes up in a unique obfuscated starting state,         which keeps the device non-functional. The uniqueness per device         is guaranteed by Physically Unclonable Function (PUF) circuitry         and other techniques at the device-specific granularity.     -   Each microelectronic device also has a uniquely defined initial         or starting Functional Reset state. The uniqueness for each         device regarding where its functional starting state is located         among the sea-of-states (as defined by state flops value) is         again influenced by the device-specific embedded features, such         as PUF, etc.     -   Additionally for each device, the rest of the very few         functional states will also be uniquely scattered among the         sea-of-states. The scattering of these functional states         differently among the devices is also determined by         device-specific parameters.     -   The burying of the few functional states amidst a sea of         obfuscated states through a flat logic hierarchy, as well as the         blending of subsequent transitions among all states in a         non-obtrusive manner, ensures the seamless behavior of the         entire state machine logic both during obfuscated mode as well         as in functional mode. This makes the understanding of the         obfuscation behavior itself (to render it ineffective), very         difficult for reverse-engineering or copying.

Referring now to FIG. 1, the diagram illustrates a system level operational processing flow of an example embodiment. The electronic device authentication and enablement system and method described herein is active, always-on, and built into the protected electronic system design. The example embodiment allows for the protected electronic device to wake-up on power-on in a non-functional obfuscated mode when the protected device is paired with a new board/system for the first time (see FIG. 1, block 210). As described in more detail below, the example embodiment generates a device and context unique obfuscation code (see FIG. 1, block 220) and uses the obfuscation code to request a corresponding authentication key from an IP owner or authorized representative of the protected electronic device (see FIG. 1, block 230). The authentication key can be provided to the protected electronic device after the IP owner successfully verifies the credentials of the protected electronic device. The authentication key received by the protected electronic device can be used to restore the protected electronic device to a fully operational mode (see FIG. 1, blocks 240-260).

For an authorized use of a protected device on or with a specific board/system, a one-time handshake (e.g., data communication) between an IP owner of the protected device and a device manufacturer/end-user is required to enable the protected device to be functional. In an example embodiment, a Physically Unclonable Function (PUF) device is used to generate a first portion of an obfuscation code used to authenticate the protected device. Physically Unclonable Function (PUF) devices are well-known physical entities that can be embodied in a physical structure and provide output that is easy to evaluate, but hard to predict. Further, an individual PUF device is typically easy to make, but its results are practically impossible to duplicate, even given the exact manufacturing process that produced it. In this respect, a PUF device is the hardware equivalent of a one-way function.

In an example embodiment, at power-on, each protected electronic device exhibits a unique per device internal n bit value or code, which represents a first portion of an obfuscation code uniquely associated with the protected device in the particular system. The n bit value or code gets created based on the manufacturing or physical characteristics of the protected device. In the example embodiment, the n parameter can be pre-defined, so the length of the first portion of the obfuscation code can be pre-defined. In a particular embodiment, the length of the first portion of the obfuscation code is 84 bits, where n=84. In one example embodiment, this first portion of the obfuscation code can be generated using a delay, or static random access memory (SRAM) based PUF, along with the associated error correcting code logic (ECC). Alternatively, in another example embodiment, the first portion of the obfuscation code can be generated by n bits of fuse, which are randomly programmable per device on the manufacturing floor. It will be apparent to those of ordinary skill in the art in view of the disclosure herein that other equivalent methods can be used to generate a value, unique to a protected device in a particular system, which can represent the first portion of the obfuscation code.

In the example embodiment, a second portion of the obfuscation code can be generated from a combination of one or more other parameters, register contents, data items, or values, including a unique device identifier (ID) associated with the protected device, a unique device manufacturing lot ID, a unique purchase order or contract ID, a unique part ID of the board or system used, a unique time/date stamp of the device manufacture, an ID associated with the geographic location of the manufacture, a unique system context ID, a unique ID of the device manufacturer or IP owner, a digital signature, a watermark, a digital rights management data object or ID, any other device specific information from the manufacturer, and any other design specific information from the IP owner. It will be apparent to those of ordinary skill in the art in view of the disclosure herein that other equivalent values can be used in a combination of values, which can represent the second portion of the obfuscation code.

In the example embodiment, the first portion of the obfuscation code as described above can be combined with the second portion of the obfuscation code as also described above to form a combined obfuscation code, or simply, the obfuscation code. When the protected device and the board/system are paired for the first time, the protected device can read the device-unique obfuscation code (see FIG. 1, block 220). The obfuscation code, as generated by the example embodiment, can represent a unique value associated with the particular protected device in the context of a particular board/system installation and manufacturing parameters. In an example embodiment, the obfuscation code can be a unique 128 bit pattern or value created with the combination component sub-values as described above. In alternative embodiments, the length of the obfuscation code can be lengthened or shortened to conform to a particular implementation. Additionally, the initially generated obfuscation code can be hashed or otherwise processed to produce an obfuscation code with desired characteristics. In an embodiment, the obfuscation code can be stored into secured Basic Input/Output System (BIOS) code, stored into a Tamper Resistant on-board Flash memory device, or stored into a Trusted Platform Module (TPM). In another embodiment, the obfuscation code can be stored into an Obfuscation State Read Only Register. In another embodiment, the obfuscation code is not stored on the board/system, but rather generated in real-time when the board/system is booted up (powered up or restarted).

As described in detail below in connection with a particular example embodiment, obfuscation technology as described herein enables a one-time authentication of the protected device in the context of the particular the board/system installation and manufacturing parameters. When a protected device and a board/system are initially paired and powered up, the example embodiment can perform the one-time authentication process. As an initial part of this process, the obfuscation code is generated as described above. Next, the obfuscation code can be read from the protected device or obfuscation components by an external system. The external system can be a network-connected computer or other separate processing platform. The external system can establish independent data communication with an IP owner or authorized representative associated with the protected device. The external system can send the obfuscation code read from the protected device to a computing system of the IP owner with a request for a device authentication key (see FIG. 1, block 230). Using any of a variety of well-known data processing techniques, the computing system of the IP owner can generate a device-unique authentication key based on the obfuscation code read from the protected device. In a particular example embodiment, the computing system of the IP owner can generate the device-unique authentication key using conventional techniques, such as encryption, steganography, hashing, or other data processing techniques. As a result, a device-unique authentication key based on the device obfuscation code can be generated by the IP owner or authorized representative associated with the protected device. The authentication key can be specific to the protected device in the context of the particular the board/system installation and manufacturing parameters. Thus, the IP owner can control the manufacture and usage of the particular protected device. In an example embodiment, the authentication key can be a 128 bit value derived from the device obfuscation code. In other alternative embodiments, the length of the authentication key can be configured to conform to a particular device/system implementation.

Once the device-unique authentication key is generated by the IP owner or authorized representative as described above, the authentication key can be provided to the protected device and/or obfuscation components in a data communication from the external computing system of the IP owner, after the IP owner successfully verifies the credentials of the protected device (see FIG. 1, block 240). In an example embodiment, the authentication key received from the IP owner can be verified or validated by the protected device to confirm that the received authentication key is authentic. The validated authentication key received from the IP owner can be programmed into the protected device and/or obfuscation components (see FIG. 1, block 250) and used by the obfuscation state machine of the example embodiment to render the protected device functional in the manner described in more detail below (see FIG. 1, block 260). For subsequent retrieval and use of the protected device on the same board/system during subsequent power-on cycles or boot-ups, the returned authentication key from the IP owner is embedded with elements of the first portion of the obfuscation code (derived from the device unique embedded n parameter bits), and then can be stored on the authorized board/system, such as stored into secured BIOS code, a Tamper Resistant on-board flash memory, or a Trusted Platform Module (TPM) and loaded from there (see FIG. 1, block 270). A non-resettable “Valid Authentication Key Programmed” flag can be set to indicate the presence of the validly programmed authentication key. In the example embodiment, the data exchange between the protected device and the IP owner occurs only once, at the very first time the protected device is paired with a specific board/system. In the example embodiment, there is no need for a subsequent authentication query exchange between the protected device and the IP owner, as long as the protected device is paired with the same board/system.

Referring now to FIG. 2, an architectural diagram illustrates the functional components provided in the example embodiment. In a typical electronic system design, a functional/operational electronic device or system (denoted protected device) 330 for a particular board or system 305 can be developed and defined in a variety of forms. For example, a digital system design can be defined as a Register-Transfer-Level (RTL) abstraction as used in hardware description languages (HDLs) like Verilog and VHDL to create high-level representations of a circuit, from which lower-level representations and ultimately actual wiring can be derived. Design at the RTL level is typical practice in modern digital design. A digital system design, such as functional/operational system 330, can also be defined as a netlist. A netlist describes the connectivity of an electronic design. As such, a single netlist is a list of all the component terminals that should be electrically connected together for the circuit to work. The design of functional/operational system 330 can also be defined in a variety of other forms as well. In any of these design definition forms, the design of functional/operational system 330 can be integrated with or embedded with the design of the embedded active obfuscation unit 300 as described herein in various embodiments. As a result, the embedded active obfuscation unit 300 can be embedded into the design and functionality of the functional/operational system 330 using any of the design definition forms in which the functional/operational system 330 is defined. As a result, the embedded active obfuscation unit 300 and the functional/operational system 330 can be integrated very early in the design process and before the functional/operational system 330 design gets exposed to the threats described above.

Referring still to FIG. 2, the embedded active obfuscation unit 300 of the example embodiment can include a Physically Unclonahle Function (PUF) 310 and error correcting code logic (ECC) 312. As described above for an example embodiment, PUF 310 can be used to generate a first portion of the obfuscation code which is used to authenticate the functional/operational system or protected device 330. In one example embodiment, the first portion of the obfuscation code can be generated using a delay, or SRAM based PUF 310, along with the associated ECC 312.

The embedded active obfuscation unit 300 of the example embodiment can include device/board identifier and manufacturing data component 314. In the example embodiment, a second portion of the obfuscation code can be generated from a combination of one or more other parameters, register contents, data items, or values, retained by the device/board identifier and manufacturing data component 314. These parameters can include a unique device identifier (ID) associated with the protected device, a unique device manufacturing lot ID, a unique purchase order or contract ID, a unique part ID of the board or system used, a unique time/date stamp of the device manufacture, an ID associated with the geographic location of the manufacture, a unique system context ID, a unique ID of the device manufacturer or IP owner, a digital signature, a watermark, a digital rights management data object or ID, any other device specific information from the manufacturer, and any other design specific information from the IP owner.

Referring still to FIG. 2, the embedded active obfuscation unit 300 of the example embodiment can include an obfuscation state register 316 and an authentication key register 318. The obfuscation code, as generated by the example embodiment, can represent a unique value associated with the particular protected device in the context of a particular board/system installation and manufacturing parameters. In an example embodiment, the obfuscation code can be a unique 128 bit pattern or value created with the combination of component sub-values as described above. In one embodiment, the obfuscation code can be stored into obfuscation state register 316 and is regenerated every time at power-on for use. The device-unique authentication key is generated by the IP owner or authorized representative based on the device obfuscation code as described above. The authentication key can be provided to the protected device via an external system. Once the device-unique authentication key is received by the embedded active obfuscation unit 300, the authentication key can be stored in authentication key register 318, and after being combined with the elements of the first part of the obfuscation code, is also updated into the secure BIOS code, or stored in an encrypted fashion either into a Tamper Resistant on-board Flash memory device, or into a Trusted Platform Module (TPM). The stored authentication key can be retrieved and used on the same board/system during subsequent power-on cycles or boot-ups of the protected device 330, and thus the need for query/exchange with the IP owner is obviated.

Referring still to FIG. 2, the embedded active obfuscation unit 300 of the example embodiment can include an obfuscation state machine 320, a valid authentication key programmed flag 319, and a functional state reached flag 322. As described in more detail below, the embedded active obfuscation unit 300 can use the authentication key to cause the obfuscation state machine 320 to transition through a pre-defined sequence of obfuscation (non-functional states) states to reach a starting functional reset state, which enables the protected device 330 to enter a functional or operational mode. Once this functional or operational mode is reached, the functional state reached flag 322 can be set to indicate the active functional state. This flag enables the protected device 330 to verify that the proper device authentication process has been completed successfully and that the device is in a normal functional mode.

Referring now to FIG. 3, a high level block diagram illustrates the functional components and processes provided in the example embodiment. As shown, the example embodiment includes the physical unclonable function (PUF) 310 and error correcting code logic (ECC) 312. As described above for an example embodiment, PUF 310 can be used to generate a first portion of the obfuscation code, which is used to authenticate the protected device 330. In one example embodiment, the first portion of the obfuscation code can be generated using a delay, or SRAM based PUF 310, along with the associated ECC 312. In the example embodiment, the PUF 310 can generate a unique but consistent PUF based ID for each electronic device. The unique PUF value can be generated using device manufacturing or physical characteristics, which produce unique internal path delays leading to unique storage values in internal storage elements. The PUF 310 can be a Delay-Arbiter type based device, or can be based on the aggregation of un-initialized wake-up contents of all the storage cells of an on-chip SRAM. Alternatively, in another example embodiment, the first portion of the obfuscation code can be generated by n bits of fuse, which are randomly programmable per device on the manufacturing floor. This alternative embodiment is shown in the bottom left portion of FIG. 3. In the example embodiment shown, 84 fuse wires can be used to program a random value for each protected device, thus providing (2⁸⁴) unique device IDs. For the integrity of this approach, the fuse programming/blowing can be performed at a silicon testing facility within the IP owner's control, using a true entropy seed feeding into a pseudo-random number generator.

As described above, the second portion of the obfuscation code can be generated from a combination of one or more other parameters, register contents, data items, or values, retained by the device/board identifier and manufacturing data component 314. The first portion of the obfuscation code from the PUF/fuse function can be augmented with the second portion of the obfuscation code comprising several other device and board specific manufacturing parameters to create the obfuscation code representing a native wake-up obfuscation state signature of the device. In an example embodiment, the obfuscation code can be a 128 bit value to enable encryption. It will be apparent to those of ordinary skill in the art in view of the disclosure herein that the obfuscation code can be any desired length as needed for particular applications. This obfuscation code can be read out by an external user system on the first pairing of the protected device and the board/system. The obfuscation code may optionally be further encrypted, if required, using standard encryption methods before the obfuscation code is read out.

The information retained by the device/board identifier and manufacturing data component 314 and used for the second portion of the obfuscation code can be used by the IP owner for several reasons. First, the reporting of the unique device ID by the manufacturer/device user, by itself, can be used to update the manufactured silicon count and thus to thwart any overbuilding attempt by a fabrication house. Secondly, once the pairing of the protected device to a board/system is reported, any future pairing of the same device (ID) with another board/system can be further investigated to determine if the new usage is for a remarked counterfeit part usage attempt. Then, such an entry of a counterfeit part into the supply chain can be prevented. A legitimate use of a refurbished part on a new board/system by an authorized supplier, will however, be approved by the IP owner with a new authentication after checking the certified credentials of the authorized supplier.

Referring to the lower portion of FIG. 3, once the obfuscation code is generated as described above, the user of the protected device can use an external system to forward the generated obfuscation code to a system of the IP owner with a request for an authentication key. In the example embodiment, the external system of the protected device user can communicate with the IP owner's system via a generic web-based secure protocol.

Referring to the lower right portion of FIG. 3, in response to the receipt of the obfuscation code and the request for an authentication key from the external system of the protected device user, the IP owner will first verify the device user supplied credentials and establish the trust of the device. Based on the device trust validation, the IP owner can generate and send the corresponding authentication key to the system of the protected device user through the same secure web protocol. In a particular embodiment, the data communication between the protected device user system and the IP owner system can be an encrypted 128 bit data transmission for added security. Upon receipt of the authentication key at the protected device, the authentication key can be programmed into the obfuscation state machine 320 of the embedded active obfuscation unit 300. In the example embodiment, the authentication key serves as the unique key to unlock the functionality of the specific protected device 330. Because the authentication key is derived from the device-unique obfuscation code as described above, the authentication key has a direct relationship with the unique wake-up protocol and the unique obfuscation state of the protected device 330.

Referring to the upper right portion of FIG. 3, the embedded active obfuscation unit 300 can use the previously generated obfuscation code to populate a pre-defined quantity of state elements (denoted state flops in FIG. 3) for obfuscation state machine 320. Each state element can represent an obfuscation (non-functional) state or a functional state of the protected device 330. In the example embodiment, the obfuscation unit 300 can select a portion of the obfuscation code, the length of which corresponds to the pre-defined quantity of state elements. In a particular embodiment shown in FIG. 3, the pre-defined quantity of state elements is 2^(k), which can be a variable number of state elements designed to meet security requirements. As such, the obfuscation unit 300 can select k bits from the obfuscation code to represent the portion of the obfuscation code that corresponds to the 2^(k) state elements as shown in FIG. 3. In a particular embodiment, the k bits can be selected from random bits of the obfuscation code field. In other embodiments, a particular bit selection pattern can be used. In the example embodiment, a pre-defined quantity (kf or k′) of the k state bits can correspond to 2^(k′) functional state elements of the protected device 330. The remaining quantity (k−kf=ko) of the k state bits can correspond to 2^(ko) obfuscation or non-functional state elements of the protected device 330. It is desired that the quantities k and ko be substantially greater than the quantity kf so the functional states can be well hidden among a huge plurality of obfuscation or non-functional states of the protected device 330. In a particular embodiment, the value k can be an order of magnitude greater than the value of kf, so that the quantity of total state elements 2^(k) is three to twelve orders of magnitude greater than 2^(kf), the quantity of total functional state elements. In the example embodiment, the pre-defined quantity of functional state elements, 2^(kf), can be driven by design.

In the example embodiment, the k bits selected from the obfuscation code by the obfuscation unit 300 can be loaded into the k state flops of the obfuscation state machine 320. In a particular embodiment, the k bits selected from the obfuscation code by the obfuscation unit 300 can be loaded into Boosted State Transition Graph (BSTG) flip-flops (e.g., state elements) of the obfuscation state machine 320. As a result of the k state flops of the obfuscation state machine 320 being loaded with the portion of the obfuscation code as described above, the obfuscation state machine 320 is configured to define a total of 2^(k) states. Given the quantity kf of functional state elements as described above, the obfuscation state machine 320 is also thereby configured to define a total of 2^(kf) functional states. As explained above, the quantity of total states 2^(k) is substantially greater than the quantity of functional states 2^(kf) in the obfuscation state machine 320.

Because the content of the obfuscation code for a particular system can be controlled by the configuration of the PUF 310 and the other components of the obfuscation code, the content of the obfuscation code can be configured to cause the obfuscation state machine 320 to initially enter an obfuscation or non-functional state. Given the initial obfuscation state, the protected device 330 will start up on power-up or reset in an initial obfuscation state. As such, the protected device 330 is forced to transition through a pre-defined set of obfuscation states before reaching a functional state for normal operation.

As described above, the obfuscation state machine 320 can be configured with 2^(k) total states using k state bits and a substantially fewer quantity of 2^(kf) functional states using kf functional state bits. As also described above, the particular configuration of 2^(k) total states and 2^(kf) functional states in the obfuscation state machine 320 is derived from the value represented by the obfuscation code. As described above, the obfuscation code represents a unique value associated with the particular protected device 330 in the context of a particular board/system installation and device manufacturing parameters. The obfuscation code for a particular protected system 330 is transferred to and used by the IP owner to generate the authentication key for the particular protected device 330. Because the particular configuration of states and functional states in the obfuscation state machine 320 is derived from the obfuscation code, the authentication key can be mathematically related to the obfuscation code and thus related to the particular configuration of states and functional states in the obfuscation state machine 320. As a result, the authentication key generated by the IP owner can represent a mapping or a particular sequence or pattern of state transitions to cause the obfuscation state machine 320 to transition from the initial obfuscation state, through a plurality of intermediate states, to a starting functional reset state for the protected system 330. The authentication key can be provided or programmed into the obfuscation state machine 320 of the obfuscation unit 300. Thus, the protected system 330 is unlocked with the authentication key and can transition from the initial obfuscation state to a starting functional reset state from which the protected system 330 can begin secure, normal operation. In a particular embodiment, the authentication key may also specify the required number c of clock cycles to be used for the protected system 330 to move from the obfuscated state to the functional state. The value of c in a particular embodiment can be a configurable parameter by the IP owner as part of the authentication key. Based on the value of c used in an embodiment, a step up/down counter with a base-line increment/decrement per clock can be created inside the device. This enables the obfuscation state machine 320 to transition across the number of states to reach the eventual starting functional reset state, all around the required number c of clock cycles.

In the event the total number of obfuscated states 2^(ko) is very large (e.g., twelve orders of magnitude larger) compared to the quantity of total functional states 2^(kf), the logic cone of input signals leading to the starting functional reset state will be very large, leading to potential circuit timing delay problems.

This issue can be mitigated by duplicating several functional reset states in place of one starting functional reset state. All of these functional reset states can be configured to converge and transition to other single or duplicated functional states. The use of replicated functional states and multiple functional reset states can overcome circuit timing delay problems caused by the use of a large quantity of obfuscated states 2^(ko) in various embodiments.

As described above, the obfuscation state machine 320 is configured to use the authentication key to cause transition from the initial obfuscation state, through intermediate states as specified by the number c of clock cycles, to one of potentially multiple starting functional reset states for the protected system 330. Once the obfuscation state machine 320 reaches a starting functional reset state, the obfuscation state machine 320 will thereafter transition only within the set of functional states, even after a hardware reset, and will never transition to a non-functional obfuscation state until the next power-on cycle. As a result, the obfuscation unit 300 is configured to securely cause the protected system 330 to reach a starting functional reset state and normal, secure operation thereafter. Once the protected system 330 transitions to a functional state, a Functional State Reached flag can be set to indicate the completion of the transition from the obfuscation state. This flag is available for other system components to verify that the protected device 330 has been properly authenticated. In a particular embodiment, it will take a minimum of 256 native, protected device clock cycles at the protected device clock speed to put the protected device into a secure, functional operational mode on every power-up cycle.

In an alternative embodiment, each of the state bits in the obfuscation state machine 320 can be configured to define more than two states. Instead of using conventional flip-flops that define only two states: 1) functional, or 2) non-functional, other multi-state devices may be used for the state bits in place of two-state flip-flops to define values corresponding to an arbitrary quantity of states, x, for each state bit. In this embodiment, the use of k state bits would enable the configuration of x^(k) states in the obfuscation state machine 320. Such an embodiment can substantially increase the quantity of obfuscation states relative to the quantity of functional states and provide an increased level of security.

Authentication Protocol in an Example Embodiment

In an example embodiment described herein, an authentication protocol is provided for use by the IP owner to first verify the genuineness of a protected electronic device and then to authorize the protected device to be functional in a particular electronic system. Until such an authorization is provided, the protected electronic device will remain non-functional when paired with the particular electronic system, such as an electronic board. The authentication protocol as described herein uses a full handshake protocol between a user of the protected electronic device and the IP owner of the protected electronic device to provision the authentication of the protected electronic device in a particular electronic system.

In the example embodiments described herein, an authentication protocol can authenticate a protected electronic device based on indicia of the device's genuineness and indicia of a pairing of the protected electronic device with a particular electronic system. When a protected electronic device is first paired with a particular electronic system, the authentication protocol of an example embodiment can perform several authentication operations to gather and validate the indicia of the device's genuineness and indicia of a pairing of the protected electronic device with a particular electronic system. For example, the authentication protocol of an example embodiment can determine when the protected electronic device is first paired with a particular electronic system. On the first such pairing, information can be recorded to document the new pairing. As a result, subsequent pairings between the same device and system can be identified and a less extensive authentication process can be used.

The authentication protocol of an example embodiment can also check and catch attempts to use a previously authorized protected device on a new spurious electronic system (e.g., board). In this manner, an unauthorized pairing between a previously authorized device and an unauthorized system can be prevented. However, in some cases, it may be appropriate to allow the pairing of a previously authorized device on a new electronic system. For example, a refurbished device may have been previously authorized. It may be appropriate to allow a refurbished and previously authorized device to be paired with a new system. The authentication protocol of an example embodiment can determine if a device is a previously authorized and refurbished device. In this case, the authentication protocol can authorize the pairing between the authorized refurbished device and a new system, once the credentials of the refurbishing house (e.g., the party responsible for the refurbished device) are established and confirmed.

The authentication protocol of an example embodiment can also detect if the electronic device itself is an unauthorized clone, a fab-overbuilt part, or a remarked chop-shop part. On such detections, the IP owner, using the authentication protocol of an example embodiment, can choose to not authenticate such an electronic device and the device will remain functionally inactive if paired with a system/board. In an example embodiment, the authentication protocol can use secure reference designs and validated hardware solutions to compare against the information provided by an electronic device user seeking to obtain authentication of a particular electronic device. These comparisons can be used to identify unauthorized devices and to establish a level of trust with authentic devices. Once trust is established by the authentication subsystem of an example embodiment using the authentication protocol as described herein, an authentication key can be generated by the IP owner or an IP owner key provisioning end-point (e.g., an authentication provisioning node).

As part of the authentication protocol of an example embodiment, the authentication protocol ensures that the protected device provider/user is compelled to connect with the IP owner of the protected device and to obtain device authentication and device/system pairing authentication prior to enabling the functionality of the device in a particular system. As a result, the device provider/user will face increased scrutiny if suspicions are raised about the authenticity of the device. Until such doubts are cleared, the authentication to enable the functioning of the device can be denied, rendering the device non-functional on the particular system/board.

The authentication protocol of an example embodiment uses a structured information exchange between the provider/user of the protected electronic device and the IP owner corresponding to the protected device. Referring to FIG. 4, a networked authentication environment 400 in an example embodiment is illustrated. The authentication protocol of an example embodiment uses two parties or two computing nodes for the authentication: 1) the device provider/user and a computing system 410 of the device provider/user at a first node (denoted as the requesting device node or RDN 410), and 2) the IP owner and a computing system 420 of the IP owner at a second node (denoted the authentication provisioning node or APN 420). Using conventional secure computing and networking technologies (e.g., the Internet 405), any device provider/user node 410 can connect (e.g., establish a data communication) with the IP owner's authentication provisioning node 420. Once this connection is established, the requesting device node 410 can provide device 330 and system/board 305 details required by the authentication provisioning node 420 to complete the authentication. In some cases, additional device 330 details, if required, can be provided by the device provider/user node 410 in an out-of-band communication 424.

Referring still to FIG. 4, the authentication subsystem 422 of an example embodiment, using the authentication protocol as described herein, can perform trust verification, device authentication, and authentication key provisioning in an automated manner. The IP owner's authentication provisioning node 420 can perform the automated trust verification, device authentication, and authentication key provisioning, based on the information provided by the requesting device node 410. The authentication provisioning node 420 can use the information provided by the requesting device node 410 to determine the grant or denial status of the device authentication key for the requesting device node 410. This method can also provide for subsequent resolution of any issue by mandating the device provider/user's direct and active participation/communication with the IP owner. After an initial successful authentication, the protected device 330 can be authenticated for subsequent power-on cycles and re-boots of the same protected device 330 on the same system/board 305 without performing a full authentication sequence with APN 420 as described above.

The authentication subsystem 422 of the example embodiments provides the assurance that a protected device 330 will never be enabled to function in an unauthorized manner. Such an expectation is very pronounced and highly demanded in mission critical applications, for example, in the realm of the defense industry, Department of Defense (DoD), NASA, and new technology sectors, including the Internet of Things (IoT), automotive applications, aerospace applications, and bio-medical devices. The authentication subsystem 422 described herein provides wide, pro-active coverage against several IP and IC piracy techniques, which are currently detected only by passive and reactive methods after the deployment of the pirated part. The authentication subsystem 422 of the example embodiments provides an opportunity for low cost device authentication based on early detection and prevention of the entry of a spurious part into the supply chain. The authentication protocol requiring a device user to obtain an authentication key from an IP owner defeats most of the current methods used in IP and IC piracy and offers protection against them. The authentication subsystem 422 described herein provides the assurance of the genuineness of the electronic devices in play.

Referring now to FIGS. 5 through 8, an example embodiment illustrates the processing operations performed as part of the authentication protocol by the authentication subsystem 422. As described herein, the authentication protocol of an example embodiment includes a data communication between the protected device provider/user using the protected device on a specific system or board for the very first time and the protected device IP owner. A successful authentication between the protected device provider/user and the device IP owner is required to unlock the obfuscated device and to make the protected device functional on the specific system/board.

As described herein, the authentication protocol of an example embodiment uses two computing nodes for the authentication: 1) the requesting device node 410, and 2) the authentication provisioning node 420. Therefore, the two parties involved in the authentication protocol of the example embodiment are:

-   -   The IP Owner who wants to verify if the protected device being         used is a genuine one and not a counterfeit/overbuilt part. On         successful verification of the protected device and the details         of the use provided by the protected device user, the IP owner         will issue an authentication key to the protected device user,         which is required to unlock the functionality of the protected         device. The IP owner may employ an automated authentication         provisioning subsystem 422, executing on a secure computing         system 420, to perform the authentication process. In another         embodiment, this automated authentication process can also be         implemented as a secure hardware module to be integrated with         other IP owner hardware functionality on the provisioning end.     -   The Device User, who is in possession of the protected         electronic device and needs to unlock the functionality of the         protected device for use on a particular system/board. The         device user can request a secure data communication connection         with the IP owner for protected device authentication. In         return, the requesting device node 410 of the device user can be         prompted by the authentication provisioning node 420 of the IP         owner to provide identification and usage details of the         protected device. These identification and usage details can         include, for example, the details of the system/board with which         the protected device is going to be paired, an identification of         the device user, an identification of the protected device, an         identification of the system/board, and any certifications or         credentials needed to prove the genuineness of the protected         electronic device procurement.

Referring still to FIGS. 5 through 8, an example embodiment illustrates the processing operations performed as part of the authentication protocol. The authentication protocol provides a data interaction between the IP owner and the protected device user. This information exchange is done securely using the conventional and established Internet access protocols (e.g., SSL/TLS). However, the data interaction and the information exchanged as part of the authentication protocol is an innovative authentication process. At the conclusion of the information exchange, based on the information provided as part of the authentication protocol, the IP owner node 420 makes a trust evaluation of the protected device user, the protected device itself, and the system/board with which the protected device is to be paired. On successful evaluation of the trust details, the IP owner provides an encrypted authentication key to the protected device user. The protected device user programs this authentication key into the protected device. The pertinent details of the authentication protocol of an example embodiment are described below as illustrated by the processing flow diagrams of FIGS. 5 through 8.

Referring now to FIG. 5 of an example embodiment, a processing flow diagram illustrates the processing performed in the example embodiment for the first-time pairing of the protected device with a specific system or board. In the case of the first-time pairing of the protected device with a specific system or board, the protected device is first powered-on on the new specific system/board. A data communication is opened between the Requesting Device Node (RDN) and the Authentication Provisioning Node (APN) (processing block 502). The RDN sends a secure message to the APN requesting device authentication (processing block 503). The RDN receives a secure message from the APN in response to the authentication request message, requesting a specific system/board identifier (processing block 504). The RDN reads the specific system/board identifier from the system/board (processing block 505). The RDN sends a secure message to the APN with the system/board identifier (processing block 506). The RDN receives a secure message from the APN requesting a protected device identifier (processing block 507). The RDN reads the protected device identifier from the protected device (processing block 508). The RDN sends a secure message to the APN with the device identifier (processing block 509). The RDN can also send additional secure messages to the APN with other user information, device information, or other system credentials or certificates (processing block 510). The RDN receives a secure message from the APN requesting a protected device query packet (processing block 511). The content of the device query packet in an example embodiment is described in more detail below in connection with FIG. 9. The RDN reads and/or assembles the device query packet from the protected device (processing block 512). The RDN sends a secure message to the APN with the device query packet (processing block 513). Processing for the example embodiment continues at the bubble 521 shown in FIG. 6 where the IP owner verifies the trust of the protected device user and the authentication key for the protected device is generated.

Referring now to FIGS. 6 and 7 of an example embodiment, a processing flow diagram 521 illustrates the processing performed by the APN, in the example embodiment for the protected device user trust verification and the authentication key generation. As shown in FIG. 6, the APN receives a secure message from the RDN requesting an authentication key (processing block 522). The APN can extract a protected device identifier and a board/system identifier from the secure message. The APN can check the device identifier for a spurious or disqualified part (processing block 524). The APN can perform a test at decision block 526 to determine if the requesting device is a spurious or disqualified part based on the device identifier and the board/system identifier. If the test performed at decision block 526 is true (yes), the APN can send a secure message to the RDN indicating that the authentication key request is denied and can terminate further authentication processing (processing block 528), pending direct sideband interaction between the protected device user and the IP owner. If the test performed at decision block 526 is false (no), the APN can transition to decision block 530. At decision block 530, the APN can test if the device identifier of the protected device is unique. If the test performed at decision block 530 is true (yes), the APN can increment a device count for this device model (processing block 532) and processing can transition to decision block 536. If the test performed at decision block 530 is false (no), processing can transition to decision block 534. At decision block 534, the APN can test if the requesting device has already been authenticated. If the test performed at decision block 534 is true (yes), processing can transition to processing block 542. If the test performed at decision block 534 is false (no), the APN can continue processing at the continuation block A 550 shown in FIG. 7 and described below.

When the processing at processing block 532 is complete, processing transitions to decision block 536. A test is performed at decision block 536 to determine if the device count has exceeded a pre-determined maximum value of devices agreed for production. If the test performed at decision block 536 is true (yes), processing can transition to processing block 542. If the test performed at decision block 536 is false (no), processing can transition to decision block 538. At decision block 538, the APN can test if the security certifications and credentials given to it for the protected device and the specific system/board are valid. If the test performed at decision block 538 is true (yes), processing can transition to processing block 540. If the test performed at decision block 538 is false (no), processing can transition to processing block 542.

At processing block 542, the request for a new authentication key for the requesting device is declined and authentication processing terminates. The next step to enable a future authentication process requires direct sideband interaction between the protected device user and the IP owner. At processing block 540, on the APN side, for this device identifier, first an Authentication Attempt Count is initialized to a value of one, and also an Authentication Time Window value is programmed. Next, the request for a new authentication key for the requesting device is granted and the new authentication key for the requesting device user is generated. Processing then terminates at the End bubble shown in FIG. 6.

If the test performed at decision block 534 shown in FIG. 6 is false (no), the requesting device identifier is not unique and the requesting device has not been previously authenticated. In this case, processing continues at the continuation block A 550 shown in FIG. 7 and described next. Referring now to FIG. 7, processing continues for the protected device user trust verification and the authentication key generation in an example embodiment. A test is performed at decision block 552 to determine if the requesting device has been previously matched to a different board or system. If the test performed at decision block 552 is true (yes), processing can transition to processing block 556. If the test performed at decision block 552 is false (no), processing can transition to processing block 554. At processing block 554, an attempt count is incremented to keep track of the number of times authentication for the protected device has been attempted. At processing block 556, additional trust credentials for the requesting device are requested from the RDN. When the processing at processing block 554 is complete, a test is performed at decision block 558 to determine if the authentication attempt count has been exceeded or the authentication time window has expired. If the test performed at decision block 558 is true (yes), processing can transition to processing block 564. If the test performed at decision block 558 is false (no), processing can transition to processing block 562.

When the processing at processing block 556 is complete, a test is performed at decision block 560 to determine if the requesting device security certifications and credentials are valid. If the test performed at decision block 560 is true (yes), processing can transition via the continuation block B 561 to processing block 540 as shown in FIG. 6 and described above. If the test performed at decision block 560 is false (no), processing can transition to processing block 564 as shown in FIG. 7.

At processing block 564, the request for a new authentication key for the requesting device is declined and authentication processing terminates. The next step to enable a future authentication process requires direct sideband interaction between the protected device user and the IP owner. At processing block 562, the request for a new authentication key for the requesting device is granted and the new authentication key for the requesting device user is generated. Processing then terminates at the End bubble shown in FIG. 7.

Referring now to FIG. 8 of an example embodiment, a processing flow diagram illustrates the processing performed in the example embodiment for validation and insertion of the authentication key into the protected device. The insertion or programming of a valid authentication key into the protected device will unlock and enable the functionality of the protected device on the particular system/board. In processing block 572, the RDN receives a secure message from the APN with the encrypted authentication key packet. The details of the authentication key packet are described below in connection with FIG. 9. The RDN receives the encrypted authentication key packet after successfully satisfying all of the verification and credentialing checks described above in connection with FIGS. 5 through 7. Upon receipt of the encrypted authentication key packet from the APN, the RDN can decrypt the encrypted authentication key packet and start the process of programming the authentication key into the protected device (processing block 573). The details of programming the authentication key into the obfuscation state machine of the protected device are described above in connection with FIG. 3. As part of the process of starting to program the authentication key into the protected device, the device hardware can unwrap the authentication key received from the APN and check to see if the individual fields of the authentication key are within the acceptable limits. If the authentication key information is not acceptable, a message will be presented to the protected device user conveying information related to the authentication failure (e.g., a hardware error code can be output, which is interpreted by the secure device driver as a message for the protected device user, the message including the reasons for the failure). Upon authentication key failure, the protected device will continue to remain in the obfuscated, non-functional state. The protected device user may make the necessary corrections and initiate another authentication request to the IP owner/APN.

If the authentication key information received from the APN is acceptable, the internal protected device hardware can set a flag to indicate that a successful authentication of the protected device by the IP owner is achieved. This flag called, “Valid Authentication Key Programmed” is set internally on the control event of successful authentication key verification by the protected device. This flag will not be reset on any kind of protected device hardware or software reset. This flag will remain persistent across power-downs/ups and boots of the system/board paired with the protected device. This persistence is achieved by storing the flag value externally to the protected device as part of an encrypted image in secure BIOS, a Tamper Resistance Flash (TRF) device, or in an existing on-board/system Trusted Platform Module (TPM) (processing block 574). In processing block 574, the validated authentication key can also be modified by the protected device hardware by replacing the unique nonce timestamp with a safe, acceptable pattern. In one embodiment this replaced portion can be bit values from randomly chosen bit locations of the device's first portion of the obfuscation code (derived from the device unique embedded n parameter bits). Other embodiments can choose other approaches to modify the Authentication key value before secure storage. The rest of the authentication key can remain the same. The modified authentication key can also be stored externally to the protected device in an encrypted fashion. For subsequent power-on and re-boot cycles, the protected device can first fetch the “Valid Authentication Key Programmed” flag from external secure storage. If the protected device determines that the fetched “Valid Authentication Key Programmed” flag is asserted (true), the protected device can then fetch the securely stored authentication key as well. As a result, the protected device can proceed without the need for an extensive authentication exchange with the IP owner for subsequent power-on and re-boot cycles, once the authentication is successfully achieved on the very first pairing of the protected device with a new system/board. After a successful authentication of the protected device as paired with the particular system/board as described above, the protected device internal hardware can perform a procedure to unlock the obfuscated, non-functional protected device and transition the protected device to a non-obfuscated, fully functional state (processing block 575). The details of programming the authentication key into the obfuscation state machine of the protected device are described above in connection with FIG. 3. The action of programming the valid authentication key into the obfuscation state machine of the protected device serves to unlock the obfuscated, non-functional protected device and transition the protected device to a non-obfuscated, fully functional state. Processing then terminates at the End bubble shown in FIG. 8.

Referring now to FIG. 9, in an example embodiment, the data structures of the exchanged device specific authentication information are illustrated. In the example embodiment, there are two basic device authentication data packets, the authentication query packet and the authentication response data packet, which are associated with the protected device user/the protected device, and the IP owner, respectively. In the example embodiment, the authentication query data packet is denoted the device query packet. In the example embodiment, the authentication response data packet is denoted the authentication key data packet. The specifics of these data packets are described in more detail below for the example embodiment. These data packets are securely exchanged between the RDN and the APN in the authentication protocol as described above.

Device Query Packet: In the example embodiment, this is the final packet provided by the RDN and is an encrypted 128 bits, which the RDN will provide to the APN. Prior to this packet transfer as described above, the RDN will transmit to the APN, using existing secure Internet Protocols (SSL/TLS), the individual components of the device and system identifying information including, a protected device identifier (ID), system/board ID, and other trust credentials, which the IP owner requires from the RDN. The encrypted device query packet is created by the protected device. In the example embodiment, the device query packet is assembled, as shown in FIG. 9, with a 96 bit nonce stamp (e.g., value) to defeat packet replay attacks. The nonce value can be generated through a combination of protected device embedded real random number generators and pseudo-random number generators along with device-based entropies for seeding. The 31 bit obfuscation state is generated by the protected device, and based on the unique device ID-based value of the protected device. The 31 bit obfuscation state value corresponds to the unique per device power-on non-functional state in which the protected device wakes up on power-up or reboot. The least significant bit (LSB) of the device query packet is a one bit “Authentication Done” indicator, which is persistent across re-boot and power-on cycles of the protected device on the same system/board. The “Authentication Done” indicator is a protected device internal value, which keeps track of the protected device having been successfully authenticated before.

Authentication Key Packet: In the example embodiment, this packet represents the encrypted authentication key generated by the APN on the successful outcome of the protected device/protected device user trust verification performed by the APN as part of the authentication protocol as described above. The authentication key packet has the same 96 bit nonce value to match with the device query packet, and thus defeats replay attack attempts. The APN can generate the N bit authorization code value as shown in FIG. 9, which the protected device checks to see if the value is indeed an acceptable value. The (32-N) bit value field, as shown in FIG. 9, defines the specific number of cycles close to which the protected device should always take to converge from its non-functional obfuscated state to its first functional state. This value is a performance metric, and in the absence of a given value, a default number of cycles is assumed by the protected device to achieve its convergence to a non-obfuscated, fully functional state. It will be apparent to those of ordinary skill in the art in view of the disclosure herein that additional values or different arrangements of data in the device query packet and the authentication key packet can be implemented within the scope of the embodiments described herein.

Referring now to FIG. 10, a processing flow diagram illustrates an example embodiment of a method 1150 as described herein. The method 1150 of the example embodiment includes: providing a protected device (processing block 1160); generating a device query packet including data representing one or more identifiers of the protected device and a particular paired system (processing block 1162); obtaining an authentication key based on the device query data packet from an authentication provisioning node using an external data communication (processing block 1164); and programming an obfuscation state machine of the particular paired system with the authentication key to cause the obfuscation state machine to transition the protected device from an initial non-functional obfuscation state to a functional state (processing block 1166).

Non-Functional to Functional State Machine Transition in an Example Embodiment

In example embodiments described herein, systems and methods are disclosed for causing an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles. Referring now to FIGS. 11 through 14, processing flow diagrams illustrate an example embodiment of a method 1201 as described herein. In the described example embodiment, a protected electronic device, such as the functional/operational system 330 described above, can be implemented with the systems and methods described below as integrated with or embedded within the design of the embedded active obfuscation unit 300 as described herein in various embodiments. Control logic within the obfuscation unit 300 and/or within the protected electronic device 330 can be used to implement the processing and data operations as described below.

Referring now to FIG. 11 at processing block 1210 for an example embodiment, the protected electronic device can be initially powered up in a protected state. On power-on in the protected state, the protected electronic device can initially use the on-device PUF component 310 and ECC circuitry 312 as described above to generate a device-unique seed value that is P bits long (or wide). Alternatively, the protected electronic device can initially use an already randomly programmed fuse vector or another form of seed value source to obtain the P bit device-unique seed value. In a particular embodiment, P can be a value greater than 64 bits, such as an 84 bit unique-per-device value. This P bit seed value is always consistent and can be automatically generated and/or retrieved on initial power-on of the protected electronic device. This P bit seed value is the root of trust for the protected electronic device in terms of its use for seeding all other protected electronic device-specific parameters used in the secure initialization process described herein for the various embodiments.

At processing block 1220 for the example embodiment shown in FIG. 11, the protected electronic device can derive K bits from a randomly positioned set of bits from the P bits of the seed value, where K is typically greater than 16 bits (processing block 1220). As described above, the K bits can be derived from randomly designed/hardwired locations of the on-device PUF component 310, ECC circuitry 312, a randomly programmed fuse vector, or another form of seed value source. The K bits can be used to define the initial (e.g., the original, starting, or wakeup) obfuscation state of the protected device. In particular embodiments, K can be in the range of 22 to 32 bits (default value 22 bits) to provide a total state count between 4 million (2²²) to 4 billion (2³²) total states in the state machine 320. Then, the example embodiment can load K state elements (e.g., flops) of the state machine 320 with values corresponding to the K bits derived from the seed value (processing block 1230). The K state elements will represent the initial obfuscation state. The example embodiment can then use a different randomly positioned set of bits from the P bits of the seed value to derive a different set of M bits, which is then used in the creation of the Starting Functional Reset State Value (processing block 1240). In a typical implementation, the value of M is much less than the values of K or P. This will ensure that the Starting Functional Reset State is well-hidden in a much greater number of obfuscation states. For example, an order of magnitude larger K compared to M will yield a six to eight orders of magnitude difference between the total number of states in the state machine 320 compared with the total number of functional states. In a particular example with M equal to two bits and K equal to an order of magnitude larger number of bits (e.g., K=2×10=20 bits), the total number of states will be one million (2²⁰) states compared to the total number of functional states, which in this example would be four (2²), which is a difference of six orders of magnitude. Similarly, with M=3, and K=30 (e.g., 3×10=30, an order of magnitude greater than M), the total number of states in the state machine 320 would be one billion states)(2³⁰) compared to the total number of functional states, which in this example would be eight (2³), which is a difference of greater than eight orders of magnitude.

Once the example embodiment has derived M bits from a randomly positioned set of bits from the P bits of the seed value, the example embodiment can create the Starting Functional Reset State Value as influenced by these M bits (processing block 1250). Another way to explain this is that the M bits underpinning the Starting Functional Reset State Value will be scattered into random bit positions in a new K bit wide vector, with rest of the (K-M) bit locations having a special relationship with the original K bits scoping the entire Obfuscation State machine. The value of the M bits chosen, combined with the rest of the associated K bit vector, produces the location of the Starting Functional Reset State in the state transition graph (STG) in a manner that is completely unique for each device. The example embodiment can save the Starting Functional Reset State Value, which is unique to each protected electronic device (processing block 1260). Each of the remaining functional states in the state machine 320 can be created by a fixed incremental and sequential delta offset from the Starting Functional Reset State Value. Such offset value can itself be derived from the original P bits wide seed value. This makes the locations of all the functional states also unique per device, as each of these remaining functional states are based on the device-unique random Starting Functional Reset State Value. Once the Starting Functional Reset State Value is generated as described above, the example embodiment can proceed, via the connection block 1270, to the processing logic shown in FIG. 12, where the states in the state machine 320 are traversed from the initial non-functional obfuscation state to the Starting Functional Reset State.

As described above, the authentication protocol, of an example embodiment described herein, can use a full handshake protocol between a user of the protected electronic device and the IP owner of the protected electronic device to provision the authentication of the protected electronic device in a particular electronic system. A successful authentication handshake between the user of the protected electronic device using the device in the particular electronic system for the very first time and the IP owner of the protected electronic device leads to the encrypted authentication key being programmed into the protected electronic device as described above. As part of this authentication protocol handshake transaction, the IP owner can specify a value corresponding to the, “Number of clock cycles to reach the Functional State.” This value enables the IP owner to specify a level of protection or obfuscation for concealing the Starting Functional Reset State among a large set of obfuscation states. As a result, the IP owner can be assured that his/her IP will be well protected. This value can be specified as part of the Authentication Key field as described above (e.g., see FIG. 9). This value is typically a power of two and is typically not less than 256. In a particular embodiment, the value can represent a number of cycles or state transitions between 256 and 4096. As described in more detail below, the example embodiment is configured to cycle through the states of state machine 320 from an initial obfuscation state to the Starting Functional Reset State in a number of cycles or state transitions that corresponds to the “Number of clock cycles to reach the Functional State” value as specified by the IP owner. In some embodiments, the actual number of state transitions may vary from the specified number by at most one cycle/state transition.

Referring now to FIG. 12 at processing block 1211 for the example embodiment, processing continues, via the connection block 1270, to where the initialization of a process is performed, wherein the process is for traversing states in the state machine 320 from the initial non-functional obfuscation state to the Starting Functional Reset State. As described above, the “Number of clock cycles to reach the Functional State” value as specified by the IP owner can be retrieved from the corresponding Authentication Key field. This value can be used in the example embodiment to determine the actual number of clock cycles or traversal cycles needed to traverse states to reach the Starting Functional Reset State (processing block 1211). This value can also be used in the example embodiment to initialize a total state range value (processing block 1211). In some cases, the actual number of clock cycles used for state traversal can be modified from the value specified by the IP owner to accommodate the particular characteristics of a specific state machine or device. A specific state machine can often provide a particular quantity of state elements or states, wherein the quantity may vary from device to device. As a result, the total quantity of state elements and the corresponding total state range value can be determined for the specific state machine or device in processing block 1211. Using the programmed “Number of clock cycles to reach Functional State” value, the example embodiment can compute a number of the state transitions needed to reach the Starting Functional Reset State and determine the Obfuscated State Start position in the total state range (processing block 1211). Based on the total quantity of states in the specific state machine (e.g., 2^(K)) and the total number of cycles determined to complete the traversal from an initial obfuscation state to the Starting Functional Reset State (e.g., 2^(N)), a state jump interval can be determined for reaching the Starting Functional Reset State in the programmed number of clocks (processing block 1221). In the example embodiment, the state machine state traversal process is based on the premise that the quantity of cycles used or states traversed to reach the end or extremity of the state value range of the state machine from the starting point of the initial obfuscation state should be the same or similar to the “Number of cycles to reach Functional State” value provided by the IP Owner.

As described above, the K bits randomly taken from PUF component 310, ECC circuitry 312, a randomly programmed fuse vector, or another form of seed value source are used to define the initial obfuscation state of the protected device. Because this K bit obfuscation state value is randomly obtained, the value can either be in the upper half or the lower half of the entire state value range of the state machine. By determining whether the obfuscation state value is in the upper or lower half of the state value range, the state machine state traversal process can be configured to operate in either a forward or backward traversal direction. The K bit obfuscation state value can be analyzed to determine if the value is in the upper or lower range. If the obfuscation state value is in the lower half of the state value range, then forward state traversal is performed to the end of the state value range by skipping a “Number of states to be skipped” count of states on each cycle, until close to the end of the state value range is reached. If the obfuscation state value is in the upper half of the state value range, then backward state traversal of the state machine is performed using the “Number of states to be skipped” count on each state transition, until close to the beginning of the state value range is reached. Once the extremities of the state range are traversed as described above, the state machine is configured to start at the initial obfuscation state. From this starting point, the state traversal is performed in the opposite direction (i.e., backward or forward) as compared with the earlier traversal direction. The state traversal process is continued in the opposite direction until the opposite end of the state range is reached. Once the opposite end of the state range is reached, the state traversal through the states of the state machine as required to be done using the number of clock cycles specified is completed.

Referring still to FIG. 12 at processing block 1231 for the example embodiment, processing continues by setting a Convergence Window indicator to active (processing block 1231). In some cases, during the state traversal operation, it is possible that a functional state may be traversed before the state machine reaches the Starting Functional Reset State. In these cases, the example embodiment is configured to disable the activation of these traversed functional states prior to reaching the Starting Functional Reset State. The Convergence Window indicator is used for this purpose. The Convergence Window indicator is set to active in processing block 1231 prior to initiating the state traversal operation and remains active prior to reaching the Starting Functional Reset State. As a result, an internal mode is set to indicate that the protected electronic device is in an “Obfuscation-State-to-First-Functional-State Convergence Window” operational status. During this operational status or window, all functional states of the state machine 320 continue to remain inactive. At processing block 1241, a Current State value is initialized to the initial obfuscation state value from the device-unique seed value. This operation effectively places the state machine 320 in the initial obfuscation state from which the state traversal process in state machine 320 can begin. At processing block 1251, a loop is initiated to transition from the initial obfuscation state to the Starting Functional Reset State by traversing the states of state machine 320. Processing then continues, through connection block 1261 shown in FIG. 13, where the state traversal operation is performed.

Referring now to FIG. 13 at connection block 1261 for the example embodiment, processing continues to decision block 1212. At decision block 1212, the Current State is tested to determine whether the current state has reached modulo—the end of the total state range of the state machine. As described above, traversal of the state machine is performed until the current state reaches the extremity of the state value range. If the Current State is not within modulo—the end of the total state range of the state machine, processing continues at decision block 1212 as the obfuscated states are traversed. When the Current State is within modulo—the end of the total state range of the state machine, processing continues at processing block 1222 where the state transitions are configured to be traversed in the opposite direction (processing block 1222). If the Current State is not within modulo—the other end of the total state range of the state machine, processing continues at decision block 1252 as the obfuscated states are traversed in the opposite direction. When the Current State is within modulo—the other end of the total state range of the state machine, processing continues at processing block 1262 where the state traversal process is complete. At processing block 1262, the Convergence Window indicator is reset to Inactive (processing block 1262). The resetting of the Convergence Window indicator enables the activation and operation of all functional states of the state machine when a traversal reaches a functional state. Once the state machine traversal is complete as described above, the state machine is configured to start at the Starting Functional Reset State. In this case, the protected electronic device has been fully authenticated and authorized to proceed from the starting functional reset state in a normal operational mode. At processing block 1272, the initialization of the protected electronic device can proceed from the Starting Functional Reset State. Thus, a system and method to cause an obfuscated non-functional device to transition to a starting functional state using a specified number of cycles is disclosed.

Referring now to FIG. 14, a processing flow diagram illustrates an example embodiment of a method 1450 as described herein. The method 1450 of the example embodiment includes: providing a protected electronic device having an embedded obfuscation unit including an obfuscation state machine (processing block 1460); obtaining a randomized seed value (processing block 1462); extracting a first number of bits from the randomized seed value, the first number of bits representing an initial obfuscation state (processing block 1464); extracting a second number of bits from the randomized seed value, the second number of bits representing a starting functional reset state (processing block 1466); determining a number of traversal cycles needed to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state (processing block 1468); and initiating a state traversal operation to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state in the determined number of traversal cycles (processing block 1470).

It will be apparent to those of ordinary skill in the art in view of the disclosure herein that the method steps or processing operations described above may be performed in alternative sequences. For example, another alternative embodiment may use the obfuscation code to request an authentication key from an authorized representative in a first external communication and then may use the board/system identifier data to request the authentication key from the authorized representative in a second external communication.

FIG. 15 shows a diagrammatic representation of a machine in the example form of an electronic device, such as a computing and/or communication system 700 within which a set of instructions when executed and/or processing logic when activated may cause the machine to perform any one or more of the methodologies described and/or claimed herein. In alternative embodiments, the machine operates as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine may operate in the capacity of a server or a client machine in server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine may be a personal computer (PC), a laptop computer, a tablet computing system, a Personal Digital Assistant (PDA), a cellular telephone, a smartphone, a web appliance, a set-top box (STB), a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) or activating processing logic that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” can also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions or processing logic to perform any one or more of the methodologies described and/or claimed herein.

The example mobile computing and/or communication system 700 includes a data processor 702 (e.g., a System-on-a-Chip [SoC], general processing core, graphics core, and optionally other processing logic) and a memory 704, which can communicate with each other via a bus or other data transfer system 706. The mobile computing and/or communication system 700 may further include various input/output (I/O) devices and/or interfaces 710, such as a display device or network interface 712. In an example embodiment, the network interface 712 can include one or more radio transceivers configured for compatibility with any one or more standard wireless and/or cellular protocols or access technologies (e.g., 2nd (2G), 2.5, 3rd (3G), 4th (4G) generation, and future generation radio access for cellular systems, Global System for Mobile communication (GSM), General Packet Radio Services (GPRS), Enhanced Data GSM Environment (EDGE), Wideband Code Division Multiple Access (WCDMA), LTE, CDMA2000, WLAN, Wireless Router (WR) mesh, and the like). Network interface 712 may also be configured for use with various other wired and/or wireless communication protocols, including TCP/IP, UDP, SIP, SMS, RTP, WAP, CDMA, TDMA, UMTS, UWB, WiFi, WiMax, Bluetooth, IEEE 802.11x, and the like. In essence, network interface 712 may include or support virtually any wired and/or wireless communication mechanisms by which information may travel between the computing and/or communication system 700 and another computing or communication system via network 714.

The memory 704 can represent a machine-readable medium on which is stored one or more sets of instructions, software, firmware, or other processing logic (e.g., logic 708) embodying any one or more of the methodologies or functions described and/or claimed herein. This also includes Tamper Resistant Flash (TRF) and Trusted Platform Modules (TPM). The logic 708, or a portion thereof, may also reside, completely or at least partially within the processor 702 during execution thereof by the mobile computing and/or communication system 700. As such, the memory 704 and the processor 702 may also constitute machine-readable media. The logic 708, or a portion thereof, may also be configured as processing logic or logic, at least a portion of which is partially implemented in hardware or firmware. The logic 708, or a portion thereof, may further be transmitted or received over a network 714 via the network interface 712. While the machine-readable medium of an example embodiment can be a single medium, the term “machine-readable medium” should be taken to include a single non-transitory medium or multiple non-transitory media (e.g., a centralized or distributed database, and/or associated caches and computing systems) that store the one or more sets of instructions. The term “machine-readable medium” can also be taken to include any non-transitory medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the various embodiments, or that is capable of storing, encoding or carrying data structures utilized by or associated with such a set of instructions. The term “machine-readable medium” can accordingly be taken to include, but not be limited to, solid-state memories, optical media, and magnetic media.

With general reference to notations and nomenclature used herein, the description presented herein may be disclosed in terms of program procedures executed on a computer or a network of computers. These procedural descriptions and representations may be used by those of ordinary skill in the art to convey their work to others of ordinary skill in the art.

A procedure is generally conceived to be a self-consistent sequence of operations performed on electrical, magnetic, or optical signals capable of being stored, transferred, combined, compared, and otherwise manipulated. These signals may be referred to as bits, values, elements, symbols, characters, terms, numbers, or the like. It should be noted, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to those quantities. Further, the manipulations performed are often referred to in terms such as adding or comparing, which operations may be executed by one or more machines. Useful machines for performing operations of various embodiments may include general-purpose digital computers or similar devices. Various embodiments also relate to apparatus or systems for performing these operations. This apparatus may be specially constructed for a purpose, or it may include a general-purpose computer as selectively activated or reconfigured by a computer program stored in the computer. The procedures presented herein are not inherently related to a particular computer or other apparatus. Various general-purpose machines may be used with programs written in accordance with teachings herein, or it may prove convenient to construct more specialized apparatus to perform methods described herein.

The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment. 

What is claimed is:
 1. An electronic system comprising: a protected electronic device; and an embedded obfuscation unit coupled with the protected electronic device, the embedded obfuscation unit including an obfuscation state machine, the embedded obfuscation unit further including control logic to: obtain a randomized seed value; extract a first number of bits from the randomized seed value, the first number of bits representing an initial obfuscation state; extract a second number of bits from the randomized seed value, the second number of bits representing a starting functional reset state; determine a number of traversal cycles needed to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state; and initiate a state traversal operation to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state in the determined number of traversal cycles.
 2. The electronic system of claim 1 wherein the randomized seed value is obtained from a Physically Unclonable Function (PUF) device, an error correcting code logic (ECC) device, or a randomly programmed fuse vector.
 3. The electronic system of claim 1 wherein the first number of bits is greater than the second number of bits.
 4. The electronic system of claim 1 wherein the first number of bits is an order of magnitude greater than the second number of bits.
 5. The electronic system of claim 1 wherein the control logic being further configured to determine the number of traversal cycles by extracting a value from an authentication key field of an authentication key packet.
 6. The electronic system of claim 1 wherein the control logic being further configured to determine a total quantity of state elements and a corresponding total state range value of the obfuscation state machine.
 7. The electronic system of claim 1 wherein the control logic being further configured to determine if the initial obfuscation state is in an upper half or a lower half of an entire state value range of the obfuscation state machine.
 8. The electronic system of claim 1 wherein the control logic being further configured to initiate a state traversal operation in a forward or backward direction.
 9. The electronic system of claim 1 wherein the control logic being further configured disable activation of traversed functional states prior to reaching the starting functional reset state.
 10. A method comprising: providing a protected electronic device having an embedded obfuscation unit including an obfuscation state machine; obtaining a randomized seed value; extracting a first number of bits from the randomized seed value, the first number of bits representing an initial obfuscation state; extracting a second number of bits from the randomized seed value, the second number of bits representing a starting functional reset state; determining a number of traversal cycles needed to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state; and initiating a state traversal operation to traverse through states of the obfuscation state machine from the initial obfuscation state to the starting functional reset state in the determined number of traversal cycles.
 11. The method of claim 10 wherein the randomized seed value is obtained from a Physically Unclonable Function (PUF) device, an error correcting code logic (ECC) device, or a randomly programmed fuse vector.
 12. The method of claim 10 wherein the first number of bits is greater than the second number of bits.
 13. The method of claim 10 wherein the first number of bits is an order of magnitude greater than the second number of bits.
 14. The method of claim 10 including determining the number of traversal cycles by extracting a value from an authentication key field of an authentication key packet.
 15. The method of claim 10 including determining a total quantity of state elements and a corresponding total state range value of the obfuscation state machine.
 16. The method of claim 10 including determining if the initial obfuscation state is in an upper half or a lower half of an entire state value range of the obfuscation state machine.
 17. The method of claim 10 including initiating a state traversal operation in a forward or backward direction.
 18. The method of claim 10 including disabling activation of traversed functional states prior to reaching the starting functional reset state. 